<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <link rel="stylesheet" href="css/logon.css">
    <title>登录界面</title>
</head>
<style>
	
	/* 清除浏览器默认边距，
	使边框和内边距的值包含在元素的width和height内 */
	* {
	    margin: 0;
	    padding: 0;
	    box-sizing: border-box;
	}
	/* 使用flex布局，让内容垂直和水平居中 */
	section {
	    /* 相对定位 */
	    position: relative;
	    overflow: hidden;
	    display: flex;
	    justify-content: center;
	    align-items: center;
	    min-height: 100vh;
	    /* linear-gradient() 函数用于创建一个表示两种或多种颜色线性渐变的图片 */
	    background: linear-gradient(to bottom, #f1f4f9, #dff1ff);
	}
	/* 背景颜色 */
	section .color {
	    /* 绝对定位 */
	    position: absolute;
	    /* 使用filter(滤镜) 属性，给图像设置高斯模糊*/
	    filter: blur(200px);
	}
	/* :nth-child(n) 选择器匹配父元素中的第 n 个子元素 */
	section .color:nth-child(1) {
	    top: -350px;
	    width: 600px;
	    height: 600px;
	    background: #ff359b;
	}
	section .color:nth-child(2) {
	    bottom: -150px;
	    left: 100px;
	    width: 500px;
	    height: 500px;
	    background: #fffd87;
	}
	section .color:nth-child(3) {
	    bottom: 50px;
	    right: 100px;
	    width: 500px;
	    height: 500px;
	    background: #00d2ff;
	}
	.box {
	    position: relative;
	}
	/* 背景圆样式 */
	.box .circle {
	    position: absolute;
	    background: rgba(255, 255, 255, 0.1);
	    /* backdrop-filter属性为一个元素后面区域添加模糊效果 */
	    backdrop-filter: blur(5px);
	    box-shadow: 0 25px 45px rgba(0, 0, 0, 0.1);
	    border: 1px solid rgba(255, 255, 255, 0.5);
	    border-right: 1px solid rgba(255, 255, 255, 0.2);
	    border-bottom: 1px solid rgba(255, 255, 255, 0.2);
	    border-radius: 50%;
	    /* 使用filter(滤镜) 属性，改变颜色。
	    hue-rotate(deg)  给图像应用色相旋转 
	    calc() 函数用于动态计算长度值 
	    var() 函数调用自定义的CSS属性值x*/
	    filter: hue-rotate(calc(var(--x) * 70deg));
	    /* 调用动画animate，需要10s完成动画，
	    linear表示动画从头到尾的速度是相同的，
	    infinite指定动画应该循环播放无限次*/
	    animation: animate 10s linear infinite;
	    /* 动态计算动画延迟几秒播放 */
	    animation-delay: calc(var(--x) * -1s);
	}
	/* 背景圆动画 */
	@keyframes animate {
	    0%, 100%, {
	        transform: translateY(-50px);
	    }
	    50% {
	        transform: translateY(50px);
	    }
	}
	.box .circle:nth-child(1) {
	    top: -50px;
	    right: -60px;
	    width: 100px;
	    height: 100px;
	}
	.box .circle:nth-child(2) {
	    top: 150px;
	    left: -100px;
	    width: 120px;
	    height: 120px;
	    z-index: 2;
	}
	.box .circle:nth-child(3) {
	    bottom: 50px;
	    right: -60px;
	    width: 80px;
	    height: 80px;
	    z-index: 2;
	}
	.box .circle:nth-child(4) {
	    bottom: -80px;
	    left: 100px;
	    width: 60px;
	    height: 60px;
	}
	.box .circle:nth-child(5) {
	    top: -80px;
	    left: 140px;
	    width: 60px;
	    height: 60px;
	}
	/* 登录框样式 */
	.container {
	    position: relative;
	    width: 400px;
	    min-height: 400px;
	    background: rgba(255, 255, 255, 0.1);
	    display: flex;
	    justify-content: center;
	    align-items: center;
	    backdrop-filter: blur(5px);
	    box-shadow: 0 25px 45px rgba(0, 0, 0, 0.1);
	    border: 1px solid rgba(255, 255, 255, 0.5);
	    border-right: 1px solid rgba(255, 255, 255, 0.2);
	    border-bottom: 1px solid rgba(255, 255, 255, 0.2);
	}
	.form {
	    position: relative;
	    width: 100%;
	    height: 100%;
	    padding: 50px;
	}
	/* 登录标题样式 */
	.form h2 {
	    position: relative;
	    color: #fff;
	    font-size: 24px;
	    font-weight: 600;
	    letter-spacing: 5px;
	    margin-bottom: 30px;
	    cursor: pointer;
	}
	/* 登录标题的下划线样式 */
	.form h2::before {
	    content: "";
	    position: absolute;
	    left: 0;
	    bottom: -10px;
	    width: 0px;
	    height: 3px;
	    background: #fff;
	    transition: 0.5s;
	}
	.form h2:hover:before {
	    width: 53px;
	}
	.form .inputBox {
	    width: 100%;
	    margin-top: 20px;
	}
	/* 输入框样式 */
	.form .inputBox input {
	    width: 100%;
	    padding: 10px 20px;
	    background: rgba(255, 255, 255, 0.2);
	    outline: none;
	    border: none;
	    border-radius: 30px;
	    border: 1px solid rgba(255, 255, 255, 0.5);
	    border-right: 1px solid rgba(255, 255, 255, 0.2);
	    border-bottom: 1px solid rgba(255, 255, 255, 0.2);
	    font-size: 16px;
	    letter-spacing: 1px;
	    color: #fff;
	    box-shadow: 0 5px 15px rgba(0, 0, 0, 0.05);
	}
	.form .inputBox input::placeholder {
	    color: #fff;
	}
	/* 登录按钮样式 */
	.form .inputBox input[type="submit"] {
	    background: #fff;
	    color: #666;
	    max-width: 100px;
	    margin-bottom: 20px;
	    font-weight: 600;
	    cursor: pointer;
	}
	.forget {
	    margin-top: 6px;
	    color: #fff;
	    letter-spacing: 1px;
	}
	.forget a {
	    color: #fff;
	    font-weight: 600;
	    text-decoration: none;
	}
</style>
<body>
    <section>
        <!-- 背景颜色 -->
        <div class="color"></div>
        <div class="color"></div>
        <div class="color"></div>
        <div class="box">
            <!-- 背景圆 -->
            <div class="circle" style="--x:0"></div>
            <div class="circle" style="--x:1"></div>
            <div class="circle" style="--x:2"></div>
            <div class="circle" style="--x:3"></div>
            <div class="circle" style="--x:4"></div>
            <!-- 登录框 -->
            <div class="container">
                <div class="form">
                    <h2>登录</h2>
                    <form>
                        <div class="inputBox">
                            <input type="text" placeholder="姓名">
                        </div>
                        <div class="inputBox">
                            <input type="password" placeholder="密码">
                        </div>
                        <div class="inputBox">
                            <input type="submit" value="登录">
                        </div>
                        <p class="forget">忘记密码?<a href="#">
                                点击这里
                            </a></p>
                        <p class="forget">没有账户?<a href="#">
                                注册
                            </a></p>
                    </form>
                </div>
            </div>
        </div>
    </section>
</body>
</html>